In the refinement of sugar, scale forms in the evaporation equipment over time and reduces the efficiency of the system. Historically, the scale has been removed mechanically or with acid and/or caustic washing procedures. These operations result in expensive down-time, labor costs and corrosion losses. Polyacrylic acid is presently being used to control scale and deposit in sugar evaporation equipment.
The instant invention chemically prevents the formation of scale in sugar evaporation equipment by the addition of polycarboxylate to the juice.
The use of polymaleic acid in the prevention of formation of alkaline metal and alkaline earth metal scale in sea water evaporators is known (U.S. Pat. No. 3,810,834). However, sugar evaporators and their chemical environment are very different from that of desalination systems. The pH of the sugar juice is usually 6.5 to 8 and the temperature in the evaporators is usually 180.degree. to 235.degree. F. (82.degree. to 113.degree. C.). The pH in desalination systems is usually 8 to 9 and the temperature is 180.degree. to 205.degree. C. in low temperature systems and 220.degree. to 240.degree. C. in high temperature systems.
U.S. Pat. No. 4,018,702 discloses amine adducts of maleic anhydride polymers as corrosion inhibitors in cooling water and boiler water systems.
The use of copolymers of acrylic acid and hydroxylated lower alkyl acrylate in inhibiting the formation and deposition of calcium phosphate in cooling water and boiler water systems is disclosed in U.S. Pat. No. 4,029,577.
Sugar evaporators and their chemical environment are very different from that of cooling water systems. The pH in cooling water systems is usually 6.5 to 8.5 and the temperature is usually 32.degree. to 70.degree. C. The quality of boiler water is excellent because the impurities are pre-removed. The pH is usually 10 to 12, the temperature 200.degree. to 250.degree. C. and the pressure 200 to 600 psi.
Phosphonobutane tri-carboxylic acids, phosphinocarboxylic acids and copolymers of acrylic acid and an hydroxylated lower alkyl acrylate have all been recommended for control of scale in recirculated cooling waters.